A multiaccess communication system without a central control device (i.e. distributed control) is disclosed in copending application Ser. No. 563,741, filed Mar. 31, 1975 and assigned to the assignee of the present invention. The system includes a plurality of transceivers connected to the communicating medium utilized in the system, each transceiver including transmitting apparatus for transmitting a signal onto the medium and receiving apparatus for receiving a signal onto the medium and receiving apparatus for receiving a signal communicated on the medium by another transceiver. Each transceiver includes a collision detector for generating a collision signal whenever a signal communicated in the medium from another transceiver is received during the time the transceiver is transmitting a signal onto the medium, the collision signal causing the interruption of the transmission of a signal onto the medium by the using device connected to the transceiver.
The network comprises sections of a coaxial cable such as disclosed in the copending application or could be any suitable medium such as fiber optic cable, radio channel or coaxial cable, etc. Since any medium includes losses, and since segments thereof may extend over large geographic ranges, various losses occur, and for that reason sections of the network are tied across repeaters.
Reference to repeaters in the aforementioned application was made for purposes of completing the embodiment since they are not necessary to practice the invention disclosed therein where short communication links are contemplated and line losses are taken out by selective design of the medium and the transceiver. However, in specific applications wherein large communication links are contenplated and selective design of the medium and transceiver cannot compensate for line losses, repeaters generally are required.
Since the system described in the aforementioned copending application is bidirectional in nature i.e., there being packets of information flowing in both directions on the cable which may arrive at the transceiver of a using device from either direction, a repeater for use in such system must be capable of bidirectional operation i.e., the repeater preferably will determine in which direction to repeat the information packet without external control. Further, the repeater, which has an incoming and repeating port, should be capable of responding to the detection of a collision by a transceiver at the repeating port and pass the occurrence of the collision back onto the incoming segment via the incoming port transceiver transmitter and cause the using device already transmitting the data packet to cease transmission.